The long term goal of our proposal is to maintain an up-to-date database of aligned amino acid and nucleotide sequences of proteins of immunological interest, so that it can be used by the world-wide research community to study one of the fundamental biological systems of human in relation to its normal functions as well as possibly associated diseases process. This database was last published in book form in 1991. Since then, it has more than tripled in size; publishing it in book form has become impossible. We have thus constructed a Web page and various database distribution formats so that researchers around the world can obtain our aligned sequence data through the electronic network system. Our analysis of this database has provided useful knowledge concerning the unique nature of CDRH3s in conferring fine specificity to antibodies, possible orientation differences between TCR interacting with MHC class I and II molecules, "split" variability peak for TCR beta chain CDR1 region and possibly other CDRs, estimation of the total number of V-genes of human and mouse kappa and lambda light and heavy chains and possibly also TCR alpha and beta chains, evolutionary differences between antibody and TCR V-genes, etc. Our initial studies of predicted 3-D structures of antibody combining sites may also be extended to the prediction of 3-D structures of TCR chains.